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https://bro-tracker.atlassian.net/browse/BIT-1298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=19207#comment-19207
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Jon Siwek commented on BIT-1298:
--------------------------------
Thanks, I see what's happening now: the process for attaching analyzers via
signature matches will buffer packet contents (excluding IP header) until a
signature matches and then later replay those packets for analysis. Since it
didn't save the IP header while buffering, those DeliverPacket calls which use
replayed content end up with a null IP_Hdr*.
I can see what it takes to fix that, but from your earlier description, you may
be able to get the information you were looking for from a different place,
e.g.:
{noformat}
diff --git a/src/analyzer/protocol/ntp/NTP.cc b/src/analyzer/protocol/ntp/NTP.cc
index 5778da9..0ba5b3f 100644
--- a/src/analyzer/protocol/ntp/NTP.cc
+++ b/src/analyzer/protocol/ntp/NTP.cc
@@ -27,6 +27,9 @@ void NTP_Analyzer::Done()
void NTP_Analyzer::DeliverPacket(int len, const u_char* data, bool is_orig,
uint64 seq, const IP_Hdr* ip, int caplen)
{
+ printf("%s:%d\n",
+ Conn()->OrigAddr().AsString().c_str(),
+ ntohs(Conn()->OrigPort()));
Analyzer::DeliverPacket(len, data, is_orig, seq, ip, caplen);
// Actually we could just get rid of the Request/Reply and simply use
{noformat}
> IP_Hdr pointer do not propagate from udp to child analyzers via DeliverPacket
> method causing a segfault
> -------------------------------------------------------------------------------------------------------
>
> Key: BIT-1298
> URL: https://bro-tracker.atlassian.net/browse/BIT-1298
> Project: Bro Issue Tracker
> Issue Type: Problem
> Components: Bro
> Affects Versions: 2.3
> Environment: Debian
> Reporter: Eric Asselin
> Priority: High
> Labels: analyzer
> Attachments: core.zip, ntp-synchronized.pcap
>
>
> From a child analyzer like NTP, the IP_Hdr pointer in the DeliverPacket
> method is empty and unusable causing a segmentation fault as soon as you try
> to access it.
> To recreate the bug, just add an "assert(ip)" inside the DeliverPacket method
> of a UDP child analyzer and the execution will fail (instead of the
> segmentation fault).
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